/**
 * Copyright (c) 2003-2006, www.pdfbox.org
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 * 1. Redistributions of source code must retain the above copyright notice,
 *    this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright notice,
 *    this list of conditions and the following disclaimer in the documentation
 *    and/or other materials provided with the distribution.
 * 3. Neither the name of pdfbox; nor the names of its
 *    contributors may be used to endorse or promote products derived from this
 *    software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE FOR ANY
 * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
 * ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 * http://www.pdfbox.org
 *
 */
package org.pdfbox.util;

import java.io.File;
import java.io.IOException;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.Iterator;
import java.util.List;
import java.util.Map;

import org.pdfbox.cos.COSArray;
import org.pdfbox.cos.COSBase;
import org.pdfbox.cos.COSDictionary;
import org.pdfbox.cos.COSInteger;
import org.pdfbox.cos.COSName;
import org.pdfbox.cos.COSNumber;
import org.pdfbox.cos.COSObject;
import org.pdfbox.cos.COSStream;
import org.pdfbox.exceptions.COSVisitorException;
import org.pdfbox.pdmodel.PDDocument;
import org.pdfbox.pdmodel.PDDocumentCatalog;
import org.pdfbox.pdmodel.PDDocumentInformation;
import org.pdfbox.pdmodel.PDDocumentNameDictionary;
import org.pdfbox.pdmodel.PDPage;
import org.pdfbox.pdmodel.common.COSArrayList;
import org.pdfbox.pdmodel.common.COSObjectable;
import org.pdfbox.pdmodel.common.PDStream;
import org.pdfbox.pdmodel.interactive.documentnavigation.outline.PDDocumentOutline;
import org.pdfbox.pdmodel.interactive.documentnavigation.outline.PDOutlineItem;
import org.pdfbox.pdmodel.interactive.form.PDAcroForm;
import org.pdfbox.pdmodel.interactive.form.PDField;
import org.pdfbox.pdmodel.interactive.form.PDFieldFactory;

/**
 * This class will take a list of pdf documents and merge them, saving the result 
 * in a new document. 
 *
 * @author <a href="mailto:ben@benlitchfield.com">Ben Litchfield</a>
 * @version $Revision: 1.2 $
 */
public class PDFMergerUtility 
{

    private List sources;
    private String destinationFileName;

    /**
     * Instantiate a new PDFMergerUtility.
     */
    public PDFMergerUtility() 
    {
        sources = new ArrayList();
    }

    /**
     * Get the name of the destination file.
     * @return Returns the destination.
     */
    public String getDestinationFileName() 
    {
        return destinationFileName;
    }

    /**
     * Set the name of the destination file.
     * @param destination
     *            The destination to set.
     */
    public void setDestinationFileName(String destination) 
    {
        this.destinationFileName = destination;
    }

    /**
     * Add a source file to the list of files to merge.
     * 
     * @param source Full path and file name of source document.
     */
    public void addSource(String source) 
    {
        sources.add(new File(source));
    }

    /**
     * Add a source file to the list of files to mere.
     * 
     * @param source File representing source document
     */
    public void addSource(File source) 
    {
        sources.add(source);
    }

    /**
     * Merge the list of source documents, saving the result in the destination file.
     *
     * @throws IOException If there is an error saving the document.
     * @throws COSVisitorException If an error occurs while saving the destination file.
     */
    public void mergeDocuments() throws IOException, COSVisitorException
    {
        PDDocument destination = null;
        File sourceFile;
        PDDocument source;
        if (sources != null && sources.size() > 0) 
        {
            try 
            {
                Iterator sit = sources.iterator();
                sourceFile = (File) sit.next();
                destination = PDDocument.load(sourceFile);
                while (sit.hasNext()) 
                {
                    sourceFile = (File) sit.next();
                    source = PDDocument.load(sourceFile);
                    try 
                    {
                        appendDocument(destination, source);
                    } 
                    finally 
                    {
                        if (source != null)
                        {
                            source.close();
                        }
                    }
                }
                destination.save(destinationFileName);
            } 
            finally 
            {
                if (destination != null)
                {
                    destination.close();
                }
            }
        }
    }


    /**
     * append all pages from source to destination.
     *
     * @param destination the document to receive the pages
     * @param source the document originating the new pages
     *
     * @throws IOException If there is an error accessing data from either document.
     */
    public void appendDocument(PDDocument destination, PDDocument source) throws IOException
    {
        if( destination.isEncrypted() )
        {
            throw new IOException( "Error: destination PDF is encrypted, can't append encrypted PDF documents." );
        }
        if( source.isEncrypted() )
        {
            throw new IOException( "Error: source PDF is encrypted, can't append encrypted PDF documents." );
        }
        PDDocumentInformation destInfo = destination.getDocumentInformation();
        PDDocumentInformation srcInfo = source.getDocumentInformation();
        destInfo.getDictionary().mergeInto( srcInfo.getDictionary() );
        
        PDDocumentCatalog destCatalog = destination.getDocumentCatalog();
        PDDocumentCatalog srcCatalog = source.getDocumentCatalog();

        if( destCatalog.getOpenAction() == null )
        {
            destCatalog.setOpenAction( srcCatalog.getOpenAction() );
        }

        PDAcroForm destAcroForm = destCatalog.getAcroForm();
        PDAcroForm srcAcroForm = srcCatalog.getAcroForm();
        if( destAcroForm == null )
        {
            cloneForNewDocument( destination, srcAcroForm );
            destCatalog.setAcroForm( srcAcroForm );
        }
        else
        {
            mergeAcroForm(destination, destAcroForm, srcAcroForm);
        }

        COSArray destThreads = (COSArray)destCatalog.getCOSDictionary().getDictionaryObject( 
                COSName.getPDFName( "Threads" ));
        COSArray srcThreads = (COSArray)cloneForNewDocument( 
                destination, 
                destCatalog.getCOSDictionary().getDictionaryObject( COSName.getPDFName( "Threads" )));
        if( destThreads == null )
        {
            destCatalog.getCOSDictionary().setItem( COSName.getPDFName( "Threads" ), srcThreads );
        }
        else
        {
            destThreads.addAll( srcThreads );
        }

        COSName names = COSName.getPDFName( "Names" );
        PDDocumentNameDictionary destNames = destCatalog.getNames();
        PDDocumentNameDictionary srcNames = srcCatalog.getNames();
        if( srcNames != null )
        {
            if( destNames == null )
            {
                destCatalog.getCOSDictionary().setItem( names, cloneForNewDocument( destination, srcNames ) );
            }
            else
            {
                //warning, potential for collision here!!
                destNames.getCOSDictionary().mergeInto( (COSDictionary)cloneForNewDocument( destination, srcNames ) );
            }
        }
        
        PDDocumentOutline destOutline = destCatalog.getDocumentOutline();
        PDDocumentOutline srcOutline = srcCatalog.getDocumentOutline();
        if( srcOutline != null )
        {
            if( destOutline == null )
            {
                PDDocumentOutline cloned = 
                    new PDDocumentOutline( (COSDictionary)cloneForNewDocument( destination, srcOutline ) );
                destCatalog.setDocumentOutline( cloned );
            }
            else
            {
                PDOutlineItem first = srcOutline.getFirstChild();
                PDOutlineItem clonedFirst = new PDOutlineItem( (COSDictionary)cloneForNewDocument( 
                        destination, first ));
                destOutline.appendChild( clonedFirst );
            }
        }
        
        String destPageMode = destCatalog.getPageMode();
        String srcPageMode = srcCatalog.getPageMode();
        if( destPageMode == null )
        {
            destCatalog.setPageMode( srcPageMode );
        }

        COSName pageLabels = COSName.getPDFName( "PageLabels" );
        COSDictionary destLabels = (COSDictionary)destCatalog.getCOSDictionary().getDictionaryObject( pageLabels );
        COSDictionary srcLabels = (COSDictionary)srcCatalog.getCOSDictionary().getDictionaryObject( pageLabels );
        if( srcLabels != null )
        {
            int destPageCount = destination.getNumberOfPages();
            COSArray destNums = null;
            if( destLabels == null )
            {
                destLabels = new COSDictionary();
                destNums = new COSArray();
                destLabels.setItem( COSName.getPDFName( "Nums" ), destNums );
                destCatalog.getCOSDictionary().setItem( pageLabels, destLabels );
            }
            else
            {
                destNums = (COSArray)destLabels.getDictionaryObject( COSName.getPDFName( "Nums" ) );
            }
            COSArray srcNums = (COSArray)srcLabels.getDictionaryObject( COSName.getPDFName( "Nums" ) );
            for( int i=0; i<srcNums.size(); i+=2 )
            {
                COSNumber labelIndex = (COSNumber)srcNums.getObject( i );
                long labelIndexValue = labelIndex.intValue();
                destNums.add( new COSInteger( labelIndexValue + destPageCount ) );
                destNums.add( cloneForNewDocument( destination, srcNums.getObject( i+1 ) ) );
            }
        }
        
        COSName metadata = COSName.getPDFName( "Metadata" );
        COSStream destMetadata = (COSStream)destCatalog.getCOSDictionary().getDictionaryObject( metadata );
        COSStream srcMetadata = (COSStream)srcCatalog.getCOSDictionary().getDictionaryObject( metadata );
        if( destMetadata == null && srcMetadata != null )
        {
            PDStream newStream = new PDStream( destination, srcMetadata.getUnfilteredStream(), false );
            newStream.getStream().mergeInto( srcMetadata );
            newStream.addCompression();
            destCatalog.getCOSDictionary().setItem( metadata, newStream );
        }

        //finally append the pages
        List pages = source.getDocumentCatalog().getAllPages();
        Iterator pageIter = pages.iterator();
        while( pageIter.hasNext() )
        {
            PDPage page = (PDPage)pageIter.next();
            PDPage newPage = 
                new PDPage( (COSDictionary)cloneForNewDocument( destination, page.getCOSDictionary() ) );
            destination.addPage( newPage );
        }
    }
    Map clonedVersion = new HashMap();
    
    private COSBase cloneForNewDocument( PDDocument destination, Object base ) throws IOException
    {
        if( base == null )
        {
            return null;
        }
        COSBase retval = (COSBase)clonedVersion.get( base );
        if( retval != null )
        {
            //we are done, it has already been converted.
        }
        else if( base instanceof List )
        {
            COSArray array = new COSArray();
            List list = (List)base;
            for( int i=0; i<list.size(); i++ )
            {
                array.add( cloneForNewDocument( destination, list.get( i ) ) );
            }
            retval = array;
        }
        else if( base instanceof COSObjectable && !(base instanceof COSBase) )
        {
            retval = cloneForNewDocument( destination, ((COSObjectable)base).getCOSObject() );
            clonedVersion.put( base, retval );
        }
        else if( base instanceof COSObject )
        {
            COSObject object = (COSObject)base; 
            retval = cloneForNewDocument( destination, object.getObject() );
            clonedVersion.put( base, retval );
        }
        else if( base instanceof COSArray )
        {
            COSArray newArray = new COSArray();
            COSArray array = (COSArray)base;
            for( int i=0; i<array.size(); i++ )
            {
                newArray.add( cloneForNewDocument( destination, array.get( i ) ) );
            }
            retval = newArray;
            clonedVersion.put( base, retval );
        }
        else if( base instanceof COSStream )
        {
            COSStream originalStream = (COSStream)base;
            List keys = originalStream.keyList();
            PDStream stream = new PDStream( destination, originalStream.getFilteredStream(), true );
            clonedVersion.put( base, stream.getStream() );
            for( int i=0; i<keys.size(); i++ )
            {
                COSName key = (COSName)keys.get( i );
                stream.getStream().setItem( key, cloneForNewDocument(destination,originalStream.getItem(key)));
            }
            retval = stream.getStream();
        }
        else if( base instanceof COSDictionary )
        {
            COSDictionary dic = (COSDictionary)base;
            List keys = dic.keyList();
            retval = new COSDictionary();
            clonedVersion.put( base, retval );
            for( int i=0; i<keys.size(); i++ )
            {
                COSName key = (COSName)keys.get( i );
                ((COSDictionary)retval).setItem( key, cloneForNewDocument(destination,dic.getItem(key)));
            }
        }
        else
        {
            retval = (COSBase)base;
        }
        clonedVersion.put( base, retval );
        return retval;
    }

    private int nextFieldNum = 1;
    
    /**
     * Merge the contents of the source form into the destination form 
     * for the destination file.
     * 
     * @param destination the destination document
     * @param destAcroForm the destination form
     * @param srcAcroForm the source form
     * @throws IOException If an error occurs while adding the field.
     */
    private void mergeAcroForm(PDDocument destination, PDAcroForm destAcroForm, PDAcroForm srcAcroForm)
        throws IOException
    {
        List destFields = destAcroForm.getFields();
        List srcFields = srcAcroForm.getFields();
        if( srcFields != null )
        {
            if( destFields == null )
            {
                destFields = new COSArrayList();
                destAcroForm.setFields( destFields );
            }
            Iterator srcFieldsIterator = srcFields.iterator();
            while (srcFieldsIterator.hasNext()) 
            {
                PDField srcField = (PDField)srcFieldsIterator.next();
                PDField destField = 
                    PDFieldFactory.createField( 
                        destAcroForm, 
                        (COSDictionary)cloneForNewDocument(destination, srcField.getDictionary() ));
                // if the form already has a field with this name then we need to rename this field 
                // to prevent merge conflicts.
                if ( destAcroForm.getField(destField.getFullyQualifiedName()) != null ) 
                {
                    destField.setPartialName("dummyFieldName"+(nextFieldNum++));
                }
                destFields.add(destField);
            }
        }
    }
    
}
